We conducted a cross-sectional questionnaire of Chinese
motorcyclists in Hong Kong, all of whom rode motorcycles
with an engine capacity>50 cc. All respondents were
recruited using a snowball-sampling technique, with the
initial referrals made by companies involved in hiring motorcyclists for domestic deliveries. The inclusion criteria
were (a) having at least 3 years of postlicence driving
experience, (b) having an annual mileage of at least
8,000 km, (c) being literate enough to read and understand
simple questions, and (d) being prepared to give an
informed consent (and signing a form to that effect). Respondents were excluded from the study if they (a) were
unable to read Chinese or (b) requested that their participation be terminated.